1. Education and professional training is the single most important factor in determining one's level of income, so obviously a lot of attention has to be given to making good choices in this regard. Unfortunately, choices need to be made before most of us are capable of choosing wisely, and bad early choices usually have a negative impact which lasts a lifetime. But such is the price of freedom.
2. Cultivate a taste for frugality and saving. See saving in a positive light - as deferred gratification, for example.
3. Aim to pay half of what your spendthrift twin would pay for anything you do buy, from food to clothes to larger items.
4. Pay off loans. The fashion for living on credit is solely for the benefit of lenders. So lend.
5. If you don't have capital or a satisfactory job, use all your spare time and brainpower to figure out what kind of paid work would be acceptable to you; and then try to find it. If you fail to find it, adjust your expectations and try again. Simply and steadfastly 'following your dream' is, more often than not, a recipe for disaster.
6. Beware of business partners.
7. Don't go into business at all unless you have extensive experience. Work for someone else.
8. Don't keep pets, and especially not a horse.
9. The rewards of having and raising children should be balanced against the fact that the fewer children you have, the more prosperous you (and they) will be.
10. Distrust all financial advice which is not blindingly obvious.